Riffle block



Nov. 29, 1938.

. I ENTOR. CHA e 1. E5 5, ULB /c//.

Patented Nov. 29, 1938 UNITED STATES PATENT oFFIcE 651,887, new Patent No. 2,086,322, dated July 6, 1937. Divided and this application June 17, 1937, Serial No. 148,637

4 Claims.

My invention consists of a rifile block construction for use in any connection where precious metal particles susceptible of amalgamation with mercury, arc to be recovered from mineral (i matter with which they may be mixed. As is well known in the art, it frequently happens in amalgamating systems of recovery, that the mercury employed becomes coated with a film of oxide or grease that prevents intimate contact between the metal particles to be recovered, for example, gold particles, and the mercury itself, under which circumstances the metal particles which fail for any reason to penetrate the film imtthe mercury, are not amalgamated and are My improved riffie block is so made that each of its grooves will hold and retain mercury and the metal particles amalgamated therewith, each of said treating grooves extending across the t-water stream used to supply the mineral and metal particles to the riflle block for treatment, and having upper and lower curved surfaces relatively to the direction of flow of the water stream, which direct one part of said stream against the upper surface of the mercury body in said groove, and direct another part of said stream against the lower surface of said mercury body. For convenient reference, the upstream surface of said mercury body is herein designated 301 as its upper surface, and the downstream surface of said mercury body is herein designated as its lower surface; similarly, the upstream and downstream walls orsurfaces of eact treating croove are respectively designated herein as its upper and lower walls or surfaces.

The eifect of so directing the water flow against the opposite upper and lower surfaces of the mercury body, subjects said mercury body to constant agitation, since the water flow is always more or less pulsating due to various causes, for example, inequality of distribution of mineral and metal particles throughout the water stream. The resultant effect on the mercury body is a vertical pulsation which by actual use I find to be most effective in breaking up any fihn that may exist on the mercury body, thereby securing intimate amalgamating contact between the mercury itself and all of the metal particles delivered into the treating groove containing the agitated mercury body, which are susceptible of amalgamation with the mercury body. At the same time that the mercury body is agitated as described, the water flow against the opposite upper and lower surfaces of the said mercury body, forcibly projects the mineral and metal particles carried by said water flow, against the opposite upper and lower surfaces of the mercury body and through said surfaces into the mercury itself. This contributes substantially to the efficient action of the rifiie block and is highly effective, since the mercury body, being subjected to substantially balanced impacts on its upper and lower surfaces, cannot react horizontally from the impacts of the mineral and metal particles in a manner to prevent its penetration by said particles, which reaction occurs where, as heretofore, the impacts of the mineral and metal particles are exerted only on the upper surface of the mercury body, and as a result its effective penetration by the mineral and metal particles has not been accomplished. My improved rifiie blocks are preferably square or rectangular, so that the bottom of any desired riffie box may be covered with them, and each riflle block is provided with as many treating grooves of the kind described and extending transversely of the direction of flow of the water stream with which the block is to be used, as can conveniently be made in the block, each of said treating grooves opening through the upper surface of the block and preferably having a depth substantially greater than half of the thickness of the block. The riflle block is preferably flat and of uniform thickness throughout, and'each treating groove is somewhat shorter than the width of the block, leaving a wall at each end of each'treating groove extending up to the plane of the top surface of the block, to retain the mercury body in the groove and also the mineral and metal particles amalgamated and 'held therein, whether the block is in its rifile box or removed therefrom, and whether the block is at rest or being moved from one location to another. Each treating groove is preferably of uniform cross-section throughout its length, the curvature of the groove transversely to effect the improved results above described, being as follows: The upper line or boundary of the groove is in the plane of the top of the block, from which line the upper surface of the groove is of convex curvature tangent with the top' plane of the block in said upper line; beginning at said tangent line, the radius of curvature of said convex portion, is very large, said radius decreasing gradually at first and then with increasing rapidity towards the lower part of the groove, until nearly the bottom of the groove is reached, where the direction of curvature of the groove surface is reversed, said groove surface continuing with concave curvature to its bottom to hold the mercury body, then upwardly to begin the lower surface of the groove, and then continuing both towards the top surface of the block and at the same time towards the upper edge of said block, the radius of curvature of the upper part of said concave curvature being of such amount, that said concave curvature intersects the top plane surface of the block at a sharp acute angle and in a line that is vertically over the lower portion of the mercury body in the groove, as a result of which the portion of the groove which is farthest downstream extends under the top surface of the block. With riffie blocks of rectangular shape, the intersecting line referred to is parallel with the tangent line referred to, said intersecting line constituting a sharp, cutting edge separating the waterflow below said edge from the water flow above it, so that the latter may continue without disturbance, eddying or hindrance of any kind to the next groove, the radius of curvature of said concave curve being such as to smoothly and without eddying or restriction, direct the water flow below said cutting edge downwardly into the treating groove and against the lower surface of the mercury body in said groove to contribute its part to the agitation above described of the mercury body. I find that unless said cutting edge is sharp and related to the concave curve as described, as, for example, where appreciable surfaces or areas are presented which extend across the flow stream, eddying of the flow stream is produced which either seriouslyimpairs or prevents the action described on the lower surface of the mercury body. I also find that it is of great importance,

that the convex curvature described, shall smoothly depart from the plane of the top of the block and smoothly change its direction as described, to effectively direct the part of the flow stream adjacent the top of the block, into the treating groove and against the upper surface of the mercury body therein; for if the action described, is not produced on both the upper and lower surfaces of the mercury body, its desired vertical agitation will not result. For example, if as heretofore proposed, there is an abrupt change of direction vertically in the upper surface of the treatment groove, allowing a cascading effect of the flow stream on top of the mercury body in the treating groove, the desired vertical agitation of the mercury body and the described effective amalgamation cannot result.

I find that my improved riflie blocks may be effectively made by molding them from rubber compound, although they may be made of any material adapted to the purpose, for example, cast iron. I preferably provide my riffle blocks with edge grooves to interlock them in position when in use, by means of suitable rods, for example of iron or steel.

This is a divisional application of my copending application Serial No. 651,887 filed January 16, 1933.

My invention will be best understood by reference to the accompanying drawings illustrating a preferred embodiment thereof, in which Fig. 1 illustrates in plan view a part of a rifiie box equipped with my riffle blocks,

Fig. 2 illustrates in plan view to an enlarged scale, one of my riflle blocks, and a part of an adjacent block,

Fig. 3 illustrates in plan view a form of looking rod for holding the rifile blocks in place when in use,

Fig. 4 is a horizontal, sectional view through the rifiie blocks, taken along the line 4-4 in Fig. 2, and

Fig. 5 shows in vertical sectional view similar to and to a larger scale than Fig. 4, a portion of one of the riflie blocks, to illustrate the action upon the mercury, of the water flowing over the rifile block.

Similar numerals refer to similar parts throughout the several views.

As illustrated in Fig. 1, the rifiie blocks 5| are preferably of relatively small size, for convenience in manufacture and handling, whereas the width of the riflieibox l0, may be relatively large, requiring a plurality of riflie blocks to complete the width of the covering of the bottom of the riille box. In view of this, and of the further fact that the length of the riffie box requires a plurality of transverse rows of said rifiie blocks to cover its bottom, it is desirable that the longitudinal joints between the riflle blocks shall be broken for successive transverse rows thereof, and to facilitate this, I employ half blocks, as indicated, at the ends of intermediate ones of said transverse rows of blocks.

In Figs. 2 and 4, I illustrate one manner in which I may construct the riflie blocks 5| referred to. Each riflie block 5! is preferably square or rectangular, and is provided with a plurality of parallel grooves 5la extending nearly from the top edge to the bottom edge across the top surface of the block, as illustrated in Fig. 2, so that each groove may contain and hold mercury for amalgamation purposes, independently of the other grooves and independently of the other riffie blocks. As illustrated in Fig. 4, each of the grooves 5la has a depth substantially more'than half the thickness of the block 5|, and is provided on the side against which the flowing water strikes, with a sharp edge 5112 from which the groove is provided with a concave wall to the bottom of the groove, so that the edge 5Ib extends over a part of the groove, the'remaining wall of the groove being convex and gradually merging with the top surface of the block 5|, so that the top part of the groove is substantially wider than its bottom part.

The block 5| may be provided on two or more of its outer edges, with grooves Me, so that when the riflie blocks are assembled on the bottom of a riffle box, as illustrated in Fig. 1, the blocks may be interlocked and held in place by locking rods 52 of the form shown in Fig. 3. The blocks 5| may be made of any material that will effectively hold mercury, for example, by molding cast iron or rubber compound.

The shape of the grooves 5la. in the riffle blocks 5|, described in connection with Fig. 4, results in the action of the water currents flowing over each riffle groove 5la, on the mercury in the rifile groove, which is generally illustrated in Fig. 5 for one of said rifiie grooves. As shown in Fig. 5, the position normally assumed by the mercury in the rifiie groove 5 la is illustrated for the body of mercury 96, as shown in full lines, which, as indicated, preferably has a depth less than half the depth of the groove. A stream of water flowing over the upper edge'of the riflle groove Ela is illustrated at 91, and part of this water stream follows the surface of the riflie groove as indicated by the arrows at 910., to engage the upper side and bottom surface of the mercury body 96, which tends to press the mercury body upwardly and also against the concave vertical surface of the riffle groove. At the same time, another part of the water stream takes the course indicated by the arrows 91b, above the mercury body 96 and just below the sharp edge 51?), and down the concave surface of the rifile groove. The water flowing along the path indicated by the arrows 91b, is thus directed downwardly on the concave surface of the riflle groove and against the lower side of the mercury body 98, so that the water pressures produced horizontally on the opposite sides of the mercury body, tend to decrease the width of the mercury body in the riflle groove 5la, and cause it to assume a distorted form indicated in dotted lines at 96c. It will be understood that the water flow over the riflle block 5| is not uniform or constant, due, for example, to pieces of mineral carried by the water stream causing variations in the flow and corresponding pulsating effects of the water streams on the mercury body 96. The result of this is a pulsating action of the mercury body 96, in the direction indicated by the arrow 98. This agitation of the mercury body breaks up the surface film on the mercury and cleans it, and results in intimate contact between the mercury and any metal particles carried by the water stream and forced by it against and into the mercury, so that most effective amalgamation results, of all the metal particles that are susceptible of amalgamation.

The riifle blocks described, may be used with riffle boxes of any form and construction, and they will operate in the efficient maner described, in any case where the metal particles carried by a water stream are susceptible of recovery by amalgamation with mercury.

While I have shown my invention in the particular embodiment above described, I do not limit myself thereto, as I may employ equivalents thereof without departing from the scope of the appended claims.

What I claim is:

1. Means for recovering metal particles from mineral consisting of a rifile block having grooves therein to contain mercury, each of said grooves having end walls and curved side walls for retaining mercury therein, one side wall of each groove being concave and extending under the top suprface of said block and presenting a sharp diverting edge to material flowing over the block in use, and the other side wall of each groove being convex and merging tangentially with the top surface of said block and curving gradually and without abrupt change of direction from the plane of the top of said block along said convex surface to the bottom portion of said groove, the surface of said groove being smoothly curved and unbroken from the top surface of said block to said diverting edge.

2. Means for recovering metal particles from mineral consisting of a riflie block having grooves therein to contain mercury, each of said grooves having end walls and curved side walls for retaining mercury therein, one side wall of each groove being concave and extending under the top surface of said block and presenting a sharp diverting edge to material flowing over the block in use, and the other side wall of each groove being convex and merging tangentially with the top surface of said block and curving gradually and without abrupt change of direction from the plane of the top of said block along said convex surface to the bottom portion of said groove, the surface of said groove being smoothly curved and unbroken from the top surface of said block to said diverting edge, said block being of molded rubber compound.

3. A rifile block for amalgamation purposes, having parallel treatment grooves in its top surface and each of said treatment grooves being of convex curvature at its upper portion beginning in a tangent line in the plane of the top surface of said block and continuing towards the bottom of said groove with gradual change of direction free from abrupt change, said convex curvature being smoothly continuous and unbroken throughout its extent from the top surface of the block and ending before the bottom of said groove is reached and there beginning tangentially and with unbroken smoothness a concave curvature continuing to and through the bottom of said groove and along the lower surface of said groove with gradual change of direction free from abrupt change, said concave curvature extending under the top surface of the block and continuing upwardly and towards the upper portion of the block and intersecting the top surface of the block in substantially the same plane as the top and beginning portion of said convex curvature and at an acute angle presenting a sharp cutting edge to a stream flowing over said groove towards said edge.

4. A rifile block for amalgamation purposes, having parallel treatment grooves in its top surface and each of said treatment grooves being of convex curvature at its upper portion beginning in a tangent line in the plane of the top surface of said block and continuing towards the bottom of said groove with gradual change of direction free from abrupt change, said convex curvature being smoothly continuous and unbroken throughout its extent from the top surface of the block and ending before the bottom of said groove is reached and there beginning tangentially and with unbroken smoothness a concave curvature continuing to and through the bottom of said groove and along the lower surface of said groove with gradual change of direction free from abrupt change, said concave curvature extending under the top surface of the block and continuing upwardly and towards the upper portion of the block and intersecting the top surface of the block in substantially the same plane as the top and beginning portion of said convex curvature and at an acute angle presenting a sharp cutting edge to a stream flowing over said groove towards said edge, said block being of molded rubber compound.

CHARLES B. ULRICH. 

